Unfortunately, Rutan is only reproducing what the X-15 did many years ago. It will be a long time before we see SSTO IMHO.
There's a big difference. He's doing it as a private citizen and with much fewer resources.
Neither Space Ship One nor the X-15 were single stage. But then neither is the shuttle. In the former two cases though, everything is reusable, unlike the Shuttle, which throws away the external tank, and the rocket boosters require considerable refurbishing, if they are even doing that anymore, after the first shuttle disaster, which involved failure of an SRB.
X-15 and SS1 both were/are carried aloft by a mother ship, which then turns around and lands, readably for the next shot. They are also alike in that neither was designed to go into orbit, but were rather technology test beds for later systems that did/will go into orbit. The Shuttle was supposed to use a fly-back booster as well, but Congress and Nixon/Ford/Carter would not pay the up front money for design, which would have saved much more money later.